example4.ml

let floyd_steinberg matrix (width, height) style =
  (*We convert the image in grey level according to style*)
  let new_matrix = grey matrix (width, height) style and
      old_color = ref 0 and new_color = ref 0 and error = ref 0 in 
  for i = 1 to width - 2 do
    for j = 1 to height - 2 do
      (*We save the color of the current pixel*)
      old_color := get_r new_matrix.(i).(j); 
      if !old_color > 127 then
      	new_color := 255
      else
      	new_color := 0;
      (*We replace the current pixel by the new color*)
      new_matrix.(i).(j) <- (!new_color, !new_color, !new_color);
      (*We calculate the error value that will be distributed to the neighboring pixels*)
      error := !old_color - !new_color;
      let color1 = fix_rgb (get_r new_matrix.(i + 1).(j) + iof (0.4375 *. foi !error)) and
      	  color2 = fix_rgb (get_r new_matrix.(i - 1).(j + 1) + iof (0.1875 *. foi !error)) and
      	  color3 = fix_rgb (get_r new_matrix.(i).(j + 1) + iof (0.3125 *. foi !error)) and
      	  color4 = fix_rgb (get_r new_matrix.(i + 1).(j + 1) + iof (0.0625 *. foi !error)) in 
      new_matrix.(i+1).(j) <- (color1, color1, color1);
      new_matrix.(i-1).(j+1) <- (color2, color2, color2);
      new_matrix.(i).(j+1) <- (color3, color3, color3);
      new_matrix.(i+1).(j+1) <- (color4, color4, color4);
    done;
  done;
  new_matrix